Escherichia coli-associated granulomatous colitis in a cat

A 6-year-old male castrated domestic shorthair cat was evaluated for a 6-month history of haematochezia, mucoid diarrhoea, tenesmus and rectal prolapse. Colonic histopathology revealed multifocal mucosal ulceration and lamina propria infiltration with large numbers of periodic acid-Schiff-positivemacrophages. Large clusters of intracellular Escherichia coli were confirmed with fluorescence in situ hybridization testing, similar to that seen in dogs with granulomatous colitis. An 8-week course of marbofloxacin resulted in resolution of clinical signs; however, recurrence occurred 4 weeks later. A 12-week course of marbofloxacin resulted in disease remission for which the cat still remains free of clinical signs (15 months). Escherichia coli-associated granulomatous colitis, although reported with rarity in this species, is an important infectious cause of chronic large intestinal disease in the cat.